LRNR - The Cellular Level or Organization

cell membrane

membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules; also known as plasma membrane

ligand

molecule that binds with specificity to a specific receptor molecule

receptor

protein molecule that contains a binding site for another specific molecule (ligand)

glycocalyx

coating of sugar molecules that surrounds the cell membrane

peripheral protein

membrane associated protein that does not span the width of the lipid bilayer but is attached peripherally to integral

glycoprotein

protein that has one or more carbohydrates attached

selective permeability

feature of any barrier that allows certain substances to cross but excludes others

concentration gradient

difference in the concentration of a substance between two regions

diffusion

movement of a substance from an area of higher concentration to one of lower concentration

isotonic

describes a solution concentration that is the same as a reference concentration

receptor mediated endocytosis

endocytosis of ligands attached to membrane bound receptors r

ribosome

cellular organelle that functions in protein synthesis

autolysis

breakdown of cells by their own enzymatic action

autophagy

lysosomal breakdown of a cells ow2n components

lysosome

membrane bound organelle originating from the golgi apparatus and containing digestive enzymes

reactive oxygen species (ROS)

a group of extremely reactive peroxides and oxygen containing radicals that may contribute to cellular damagem

mutation

change in the nucleotide sequence in a gene within a cells DNA

cytoskeleton

“skeleton” of a cell; formed by rod like proteins that support the cells shape and provide, among other functions, locomotive abilities

centriole

small, self-replicating organelle that provides the origin for microtubule growth and moves DNA during cell division

nuclear envelope

membrane that surrounds the nucleus; consisting of a double lipid-bilayernuc

nuclear pore

one of the small, protein lined opening found scattered throughout the nuclear envelopen

nucleolus

small region of the nucleus that functions in ribosome synthesis

DNA polymerase

enzyme that functions in adding new nucleotides to a growing strand of DNA during DNA replication

Helicase

enzyme that functions to separate the two DNA strands of a double helix during DNA replication

genome

entire complement of an organisms DNA found within virtually every cell

gene expression

active interpretation of the information coded in a gene to produce a functional gene product

gene

functional length of DNA that provides the genetic information necessary to build a proteinpro

proteome

full complement of proteins produced by a cell (determined by the cell’s specific gene expression)

messenger rna

nucleotide molecule that serves as an intermediate in the genetic code between DNA and protein

promoter

region of DNA that signals transcription to begin at that site within the gene (TATAA BOX)

RNA Polymerase

enzyme that unwinds DNA and then adds new nucleotides to a growing strand of RNA for the transcription phase of protein

polupeptide

chain of amino acids linked by peptide bondsri

ribosomal RNA

rna that makes up the subunits of ribosomes

translation

process of producing a protein from the nucleotide sequence code of an mRNA transcript

polyribosome

simultaneous translation of a single mRNA transcript by multiple ribosomes

diploid

condition marked by the presence of a double complement of genetic material (two sets of chromosomes, one set inherited from each of two parents)

homologous

describes two copies of the same chromosome (not identical) one inherited from each parent

somatic cell

all cells of the body excluding gamete cells

cell cycle

life cycle of a single cell, from its birth until its division into two new daughter cells cu

cytokinesis

final stage in cell division where the cytoplasm divides to form two separate daughter cells

interphase

entire life cycle of a cell, excluding mitosis

mitosis

division of genetic material during which the cell nucleus breaks down and two new fully functional nuclei are formedG

G0 Phase

phase of the cell cycle usually entered from the G1 phase; characterized by long or permanent periods where the cell does not move forward into the DNA synthesis phase

G2 Phase

third phase of the cell cycle, after the DNA synthesis phasec

centrosome

cellular structure that organizes microtubules during the cell division

miotic spindle

network of microtubules, originating from centriole that arranges and pulls apart chromosomes during mitosis

kinetochore

region of a centromere where microtubules attach to a pair of sister chromatids

metaphase plate

linear alignment of sister chromatids in the center of the cell which takes place during metaphase

metaphase

second stage of mitosis (and meiosis) characterized by the liner alignment of sister chromatids int eh center of the cell

telophase

final stage of mitosis (and meiosis) preceding cytokenesis characterized by the formation of two new daughter nuclei

anaphase

third stage of mitosis (and meiosis) during which sister chromatids separate into two new nuclear regions of a dividing

cleavage furrow

contractile ring that forms around a cell during cytokinesis that pinches the cell into two halvesP

prophase I

the chromosomes condense and become more coiled, pair up, the chromatids of one chromosome pair up with the chromatids with another chromosome to enable an exchange of genetic material with each other, genetic recombination/crossing over

metaphase I

spindle fibers move towards the opposite poles and the chromosomes paired from prophase I tend to align themselves at the equatorial plane anap

anaphase I

the contraction of the spindle fibers located at the opposite poles results in pulling of the paired chromosomes apart. The chromosome pairs detach and drift towards the opposite poles, chromosomes obtained after crossing over is called a dyad

telophase I

chromosomes at the poles begin to unwind and become thread life, the nuclear envelope develops around each of these chromosome sets

cytokinesis

a contraction develops in between the cell dividing the cell into two (each cell with one chromosome set)

prophase II

the nuclear envelopes break and cease to be visible the spindle fibers are formed and the chromosomes tend to condense resultign in coiling

metaphase II

there is a binding between the spindle fibers and the centromeres. This results in the alignment of the chromosomes on the equatorial plane

anaphase II

the spindle fibers that are attached to the centromeres and tend to pull the chromatids away from each other towards the opposite poles at each pole the chromosome number is haploid

telophase II

the unwinding of the chromosomes takes place followed by disappearance of spindle fibers and development of the nuclear components (nuclear envelope and nucleoli)

cytokinesis II

a narrow structure develops from the border of the cell that deepens further to divide the cell into two daughter cells

stem cells

cell that is oliigo- multi- or pluripotent that has the ability to produce additional stem cells rather than becoming further specialized

totipotent

embryonic cells that have the ability to differentiate into any type of cell and organ in the body

multipotent

describes the condition of being able to differentiate into different types of cells within a given cell lineage or small number of lineages such as a red blood cell or white blood cell

pluripotent

describes the condition of being able to differentiate into a large variety of cell types

unipotent

describes the condition of being committed to a single specialized cell type

oligopotent

describes the condition of being more specialized than multipotency the condition of being able to differentiate into one of a few possible cell types